MySQL IFNULL() Function

The MySQL IFNULL() function is used to provide alternate value if an expression is NULL. This function returns the expression, if the expression is NOT NULL.

Syntax

IFNULL(expression, value_if_null)

Parameters

Return Value

Returns expression, if expression is NOT NULL. Returns value_if_null, if expression is NULL.

Example 1:

The example below shows the usage of IFNULL() function.

mysql> SELECT IFNULL('Paris', 'London');
Result: 'Paris'

mysql> SELECT IFNULL(NULL, 'London');
Result: 'London'

mysql> SELECT IFNULL(5/0, 'Dividing by 0 returns NULL');
Result: 'Dividing by 0 returns NULL'

mysql> SELECT IFNULL(DATE('2018-10-15'), '2018-10-31');
Result: '2018-10-15'

mysql> SELECT IFNULL(DATE(NULL), '2018-10-31');
Result: '2018-10-31'

Example 2:

Consider a database table called Product with the following records:

If the OrderQuantity is optional and can contain NULL values. The statement mentioned below will give NULL value.

SELECT *, Price * (StockQuantity + OrderQuantity) AS Inventory  
FROM Product;

This will produce the result as shown below:

To avoid such situations, the IFNULL() function is used which provides alternative value to the column if it contains NULL value.

SELECT *, Price * (StockQuantity + IFNULL(OrderQuantity, 0)) AS Inventory
FROM Product;

This will produce the result as shown below: